A rectangular array is really just one array, is it not? From a syntax point it looks like a multidimensional array but really it's just a single linear piece of memory, so just cast it:
void main() { int[2][4] table; table[0][] = 0; table[1][] = 1; table[2][] = 2; table[3][] = 3; auto x = cast(int[])table; assert(x == [0, 0, 1, 1, 2, 2, 3, 3]); }